#!/usr/bin/env python
# -*- coding: utf-8 -*-

'''断言'''

def check_len(obj):
    return len(obj) > 3
#assert 表达式(返回值为True或False), 错误消息(表达式返回False时显示)
assert check_len("jack dom"), "length must be greater than 3"
assert check_len("dom"), "length must be greater than 3"  #AssertionError: length must be greater than 3
assert check_len("dom"), "length must be greater than 3"  #AssertionError: length must be greater than 3
